Retort/furnace for processing large scrap tires

ABSTRACT

Disclosed is a batch pyrolysis reactor for the recovery of pyrolysis products by batch processing waste material. The reactor includes a heating chamber, a removable retort for insertion into and withdrawal from the heating chamber, and a control unit for cycling the temperature of waste material in the pyrolysis chamber. The retort includes a pyrolysis chamber having an opening for receiving and extracting solids.

BACKGROUND OF THE INVENTION

The 1970's have proved to be a monumental time in the life of a scrap tire. That is when the United States became more interested in recycling in general. Prior to this time most tires were unwanted and piled up in our landscapes, buried or put in places where they'd be out-of-site. For many, the unwanted tires were an abundant resource. They were used for simple tire swings, barriers, landscaping and even barge operators thought they would be great to protect their boats. For the most part, before 1970 our nation generally didn't want the tires.

This uninterested position resulted in piles of tires building up all over our country. It wasn't until a few fires took place that the complications of massively piling these tires started to become noticed. Days often turned to months with some turning to years in what it took to put out these tire fires. The oil left behind acted as a fuel and putting out such fires became difficult. Then the oil took on a second hazard by seeping into the underlying ground making clean up even more cumbersome, costly and time consuming. In other parts of the country another disaster was taking place in the quiet vastness of our landscapes. Mosquitos and other insects found a new home. Breading grounds, like tire fires, became a public nuisance that affected cattle and human populations.

Since the 1960's our nation has been adding almost one tire per person equal to our country's population on an annual basis. This is just for passenger car tires. When commercial tires are added the numbers grow to over 425 million tires added to the piles each year. All of this has hit the news in recent decades and when the 1970's were upon us we became recycle conscious. All of a sudden the scrap tire became a valuable resource and there were plenty of them readily available. Like any first solution to a problem the simplest of application of science to a problem yields simple solutions. This lead to using the tires as a fuel source, the creation of landscape material making its way to playgrounds all around the country and crumb rubber, just to name a few.

Like most simple solutions, many jumped on the bandwagon and produced such products because of the ease of using a seemingly endless supply of scrap tires while also being able to take credit for being ‘environmentally green’. As time progressed the United States Environmental Protection Agency concluded that using the tires as a fuel source in cement and pulp plants produced too many harmful emissions. As of 2006 as many as 40 percent of scrap tires generated were being used as such a fuel. This use has been on a steady decline and is anticipated to be outlawed sometime in the near future. Like any first round of solutions second generation solutions we soon to come by a future round of improved applications of science.

The use of pyrolysis principles is beginning to surface eliminating emission issues and the creation of a whole breath of new off-take products. Two methods of utilizing retort fundamentals have surfaced. The first is called ‘continuous’ processing where scrap tires are cut up into 2-3 inch pieces, fed into a retort/furnace, heated to the point of decomposition without the aid of oxygen leaving carbon, steel, gas and oil. Alternatively, the second method is conducted in ‘batches’ where tires can be put in whole eliminating all upfront cutting and slicing costs. The tires are heated typically for longer periods of time versus the continuous processing machines producing an even higher level of off-take products with greater pricing capabilities. In conclusion, the public awareness of the values of scrap tires has improved greatly in recent decades and the conversion of such tires into valuable products is well on its way of the evolutionary cycle.

Examples of pyrolysis equipment are described in US patent publication 20060163053 and in U.S. Pat. No. 8,006,758.

What the general public is quite aware of is what is happening in the Powder River Basin area of Wyoming. Fifteen mines dig up coal for delivery throughout the United States to fuel electric power plants and a host of other uses. As the mining companies have driven the processes of extracting the coal to a high level of efficiency the solution has been based on one main principle: Make the trucks as big as possible to haul up to 400 yards of soil in a single load. All the mines have adopted the same philosophy as tires have grown from 10 feet in diameter to nearly 13 feet today and can weigh up to 7,000 pounds when discarded. These vehicles are used around the clock and generate between 4,500 to 5,000 scrap tires annually. It's important to remember the basic premise for which these tires are made. Their harsh use means they must be durable and built to be indestructible! The simple plys and bands of steel cables common in passenger car tires give way to steel cages and bead wire around the wheel hub up to 3″ in diameter. What is also common with all the mines is the inability to discard these large tires in a manner acceptable to the State's Department of Environmental Quality guidelines.

There has been extensive research and testing to slice, cut, chip and shred these behemoth tires without favorable results. The only formidable use of such tires over the past few years has been for cattle watering tanks They are created by ‘bagel cutting’ the tires, pouring a cement pad and placing the half cut tire on top of the cement filling the hub area of the tire. This has resulted in two problems. First, the need for water tanks has dwindled to a minimum as the market has become saturated and secondly, all of the top halves of the cut tires are piling up waiting for proper disposal. The lack of disposal solution for the mines has resulted in the remaining tires being buried. This singled out model of the coal mine industry in Wyoming is common throughout the world.

This invention addresses the problem of disposal of such large tires by utilizing the pyrolysis processes perfected over the past two decades in a batch mode to provide the first known method of acceptable disposal. As described above, the benefit of the batch process method is the ability to process the tires whole. The retort/furnace equipment required to conduct the decomposition of these tires is defined in this patent. It is unique to such comparable machines used to process passenger car tires to accommodate the massive 14,000 pounds of tires with the added benefit of having the capability to process small tires of all sizes as well.

SUMMARY

The current method of recycling scrap tires involves slicing, chipping, burning and grinding. This is possible because the tires that average 22-24 pounds each are on a smaller scale than the equipment used to processes them. To expand the ratio of equipment capability versus tire size to handle a 7,000 pound tire is insurmountable. This is why the retort method utilizing pyrolysis processes is the emphasis of this patent. The ability to process the tires ‘whole’ decreases complexity, expense and creates an opportunity to process with repeatability in a safe environment.

A retort is an airtight vessel in which substances are heated for a chemical reaction producing vapor products to be collected in a collection vessel or for further processing. The retort in this patent is vessel approximately 13′6″ in diameter and 9′ in internal height that sets in a larger similar furnace vessel that contains numerous burners to provide the a heat source for the pyrolysis process to take place. The ability to remove the retort from the base furnace unit aids in loading and unloading to allow the furnace to be utilized around the clock. The retort/furnace vessel has the ability to capture the vapors given off by the heating of the tires for processing into oil and gas products. The retort/furnace contains a lid for containment of the heat applied by the furnace and directional flow of the vapors produced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional view of a retort/furnace.

FIG. 2—retort/furnace Circulation Within The retort/furnace.

FIG. 3 depicts a cross-sectional view of a retort/furnace configured with large and baled tires.

FIG. 4 depicts a cross-sectional view of a retort/furnace configured With baled tires.

FIG. 5 depicts a cross-sectional view of a retort/furnace showing the location of burners.

FIG. 6 depicts a cross-sectional view of a retort/furnace of FIG. 1 showing additional details of the combustion chamber surrounding and separated from the retort chamber.

DETAILED DESCRIPTION

The retort/furnace consists of several components that collectively provide the environment to break down the tires being processed. The primary components include:

-   -   Furnace—the furnace is a cylindrical enclosure with an opening         on top to allow insertion of the retort component. The furnace         is the source for all heat applied to the surrounding outer         sides and at the bottom of the outside of the retort walls. The         furnace includes sight windows for direct observation of each         burner.     -   Retort—the retort is a similarly shaped vessel to the         cylindrical furnace that is smaller in size to allow insertion         into the furnace. The outside walls of the retort are exposed to         the direct heat source as supplied by the burners and the inside         containing the tires and subsequent carbon, steel, oil and gas         off-take products. The retort is removable from the furnace via         an overhead lifting devise for ease of loading and unloading.         The retort shall be made of stainless steel, or similar         metallurgy properties, to accommodate the high temperatures         needed to support the pyrolysis process.     -   Lid—the lid serves a valuable function as it contains the heat         and contents within the retort during operation while also         providing access for loading and unloading of the vessel. The         environment within the retort during operation requires the lid         to contain a seal to keep the vapors from escaping while also         including a clamping mechanism to tighten the connection.     -   Burners—six burners are included with three providing coverage         on the bottom spaced 120 degrees apart and three additional         units half way up the sides of the furnace spaced 120 degrees         apart and offset 60 degrees from those on the bottom. The         burners shall have a heat capacity of 750,000 BTU's each and         allowed to operate collectively with all six units at once or         the ability to vary each one. The primary heat source shall be         set up to accommodate varying fuel sources for the early cycle         of operation then transfer over to operation with the synthetic         gas produced by the pyrolysis process.     -   Spacers—the primary purpose of applying heat to the scrap tire         is to break down the rubber based structure of the tire         material. The addition of spacers at the bottom of the retort         vessel for the first tire to rest on along with spacers between         the additional tires allows for increased surface exposure to         the internal heat. This feature reduces the time needed to fully         break down the tires into their four new off-take materials.     -   Nitrogen Injector—the premise of pyrolysis is based on an oxygen         free environment. When the lid is closed the internal space of         the retort contains oxygen. Nitrogen gas is injected into the         retort in a calculated volume to allow the displacement of the         heavier oxygen molecules with those of the nitrogen gas. The         oxygen is forced into the downstream condensing system through         this operation. As the burners are turned on and the retort         begins to heat the internal pressure increases enough to keep         the oxygen from back drafting into the retort vessel.     -   Circulation Fan—the more evenly distributed the application of         heat produced from the burners the more efficient the breakdown         of the scrap tires. To aid in the internal movement of air a fan         mounted in the lid provides heat distribution with the added         assistance from several circulation turning vanes also mounted         on the lid. The key to the use of the fan is to not operate at         such great speeds to stir up the carbon remains to where they         become airborne and mix with the vapors. The fans primary value         is realized during the earlier stages of the heat cycle and         reduced as the presence of carbon increases.     -   Combustion Chamber—the combustion chamber (furnace vessel)         surrounds the retort and heats the retort and waste material         placed therein. During a pyrolysis period, combustion gases are         exhausted through the exhaust and do not mix with the contents         of the pyrolysis chamber formed in the retort. Similarly,         nitrogen is injected into the retort and pyrolysis gases are         removed from the retort without mixing with anything in the         combustion chamber. 

1. A furnace vessel that provides a heat source to a retort vessel.
 2. A retort vessel that contains scrap tires that is inserted into claim No.
 1. 3. A lid that seals the retort and furnace vessels stated in claims No. 1 and
 2. 4. A heat source included in claim No. 1 that provides the heat needed to conduct the pyrolysis process used in claim No.
 2. 5. Spacers to lift the bottom located tire in the retort and separate any additional tires placed on top or on the sides placed in claim No.
 2. 6. Nitrogen injection system applied to claim No. 2 to evacuate all oxygen contained within claim No. 2 prior to the application of the heat source in claim No. 4 as contained within claim No.
 1. 7. A circulation fan contained within claim No. 2 and mounted within the lid of claim No.
 3. 8. Multiple individual turning vanes to guide internal circulation within claim No. 2 and supporting circulation generated by claim no.
 7. 9. The ability to insert smaller tires within the void spaces of the larger tires while still operating in the same manner.
 10. The ability to use the retort vessel without the very large tires and utilize with numerous bales of smaller tires while still operating in the same manner.
 11. A batch pyrolysis reactor for the recovery of pyrolysis products by batch processing waste material comprising, a heating chamber having a chamber opening, having a removable lid for obtaining access to the chamber opening, having heating ports for receiving combusted gases for heating the heating chamber and having an exhaust for exhausting combusted gases, a removable retort for insertion into and withdrawal from the heating chamber through the chamber opening and for enclosure in the heating chamber by the lid for heating of the retort, the retort including, a pyrolysis chamber having an opening for receiving and extracting solids, a port for porting pyrolysis gas from the reactor during a pyrolysis period to leave a solid residue in the pyrolysis chamber after the pyrolysis period, a control unit for cycling the temperature of waste material in the pyrolysis chamber over a pyrolysis period whereby after the pyrolysis period the retort is removed from the heating chamber and the solid residue is removed from the retort. 